Cycles Render on GT750 GPU (MacBook Pro) 2GB Graphics - 2.79 Blender
OpenCL does not work (yet?) for Blender on MBP with NVidia. It worked with CUDA for me on mid 2014 MBP with GT750M 2GB Nvidia but I had to install the latest NVidia drivers and CUDA, however the result was extremely disappointing, pretty much the equivalent of single core CPU rendering instead of 8-core! Don't waste your time with this with the GT750M.

Since the NVidia GEForce drivers are not stamped by Apple, they are hard to find even on the NVidia website. I used this site as source of the NVidia link! https://www.tonymacx86.com/forums/graphics.13/

At the time of this post, the latest drivers are http://www.nvidia.com/download/driverResults.aspx/130460/en-us

... which also includes the link to download CUDA...